Abstract
The role of male pheromones in estrous cyclicity was studied in mice selected for different reproductive traits. When females are exposed to males of their own strain, estrous cycles are highly regular in females selected for increased embryo survival (line E). In contrast, cycle regularity is reduced by exposure of line E females to males from a strain characterized by irregular estrous cycles (line CNβ). To investigate the inhibition of estrous cyclicity and the role of androgen in this phenomenon, line E females were housed in the olfactory presence of E males and later rehoused with one of the following: intact or castrated males of line E (homogenotypic condition) or line CNβheterogenotypic condition) or castrated CNβ males provided with testosterone replacement. A final exposure to homogenotypic (line E) males was provided. Estrous cyclicity was decreased when line E females were rehoused with intact or castrated CNβ males. Metestrus was prolonged by intact CNβ males, whereas diestrus was prolonged in the presence of castrated CNβ males. Androgen treatment did not enable castrated CNβ males to prolong metestrus. These results demonstrate that: 1) heterogenotypic pheromones inhibit estrous cyclicity in line E; and 2) the inhibitory influence of line CNβmales on line E estrous cyclicity is mediated by factors in addition to or other than testosterone. Β© 1993 WileyβLiss, Inc.